1. Field of the Invention
This invention relates to a cylinder, preferably an impression cylinder for cooperation with a rotogravure printing cylinder. More particularly, the invention relates to a cylinder that includes a shell that is freely rotatably mounted on a stationary axle by means of annular members carrying a plurality of spaced rolling element bearings, wherein at least the intermediate ones of the annular members are radially displaceable in order to deflect the shell of the cylinder in a direction transverse to its longitudinal axis.
2. Description of the Prior Art
It is often desired to deflect a rotatable cylinder transversely relative its longitudinal axis so that the cylinder bows outwardly at the center and applies uniform pressure to a second cylinder which contacts the first-mentioned cylinder along a generatrix and has also been deflected, or that tends to deflect the first-mentioned cylinder. The pressure applied should compensate for the deflection of the second cylinder or should prevent a deflection of the first-mentioned cylinder. For example, in a rotogravure press the printing cylinder applies a substantial pressure to the impression cylinder and causes the latter to be radially deflected because it has lower flexural stiffness. That deflection often prevents a satisfactory imprint to be achieved.
German Patent Specification 15 11 224 discloses a deflectable cylinder that includes a shell rotatably mounted by means of rolling element bearings on a tubular axle, and the shell is adapted to be deflected by eccentric tie rods extending into the interior of the axle.
Published German Application 22 57 947 describes a deflectable cylinder that includes a shell mounted on annular members by means of rolling element bearings. The shell is rotatably mounted on stacks of leaf springs, which constitute the axle and which are adapted to be forced against each other in order to deflect the shell. The shell is deflected by a deflection of the axle, which consists of a tubular stack of leaf springs, and it is difficult to bend the shell exactly to the desired curvature. Moreover, the axle of such a cylinder has a substantial resilience and, as a result, only a low flexural stiffness, so that it cannot be satisfactorily used if the cylinder is required to apply substantial compressive stresses to a cooperating cylinder.
German Patent Publication 20 33 515 discloses a cylinder that can be deflected by the application of transverse forces to the journals protruding beyond the bearings.
German Patent Specification 29 42 002 discoses a cylinder that includes a shell freely rotatably mounted on a rigid axle by means of bearing elements having pockets for the application of hydrostatic pressure. The bearing elements have cylindrical bores, which receive piston-like pins that are connected to the axle. The cylindrical bores and the pockets are supplied with a fluid through the pins for the application of hydrostatic pressure. In that cylinder construction it is difficult to prevent tilting of the shell and it is also difficult to supply the fluid to and to withdraw it from the bearing elements and to control the bearing elements by means of the fluid.
It is an object of the present invention to provide a transversely deflectable cylinder that has a high flexural stiffness and that also permits a controlled transverse deflection of the shell of the cylinder, relative to its longitudinal axis, to be achieved in a simple manner.